基于一面两孔定位夹紧一体化的高精度气动随行夹具研究

详细介绍一种基于一面两孔定位的新型高精度气动夹具.该夹具中,采用自定心弹性开口套作为定位销,代替圆柱销和菱形销并兼作夹紧元件.阐述弹性开口套的结构、工作原理、夹紧过程及特点.和传统的一面两孔定位方式对比可知,该新型高精度气动夹具具有定位精度高、结构紧凑、操作方便、工作效率高、劳动强度低等优点,特别适合作中批量和大批量生...     

一种基于一面两孔定位和夹紧一体化的新型高精度气动夹具的设计

介绍了传统一面两孔组合定位实现工件夹紧的原理,并进行了定位、误差分析,指出其存在的缺点.提出一种将定位销兼作夹紧元件的新型气动夹具,并介绍其定位夹紧原理、结构特点、气动原理和装夹过程.新型夹具具有定位精度高、结构紧凑、操作方便、工作效率高、劳动强度低等优点.     

一种用于砂芯托盘的精确定位装置

针对铸造厂砂芯自动化生产线上机器人上料和下料工位放置砂芯的托盘需要精确定位的问题,介绍一种用于托盘精确定位的四面夹紧机构,包括定位和夹紧装置、气动控制装置;变频输送辊道对砂芯托盘进行初次粗定位,四面夹紧机构实现精确定位。现场运行表明,该系统能满足托盘的定位精度要求,避免了由于托盘定位不准可能造成机器人夹具损坏砂芯的问题。     

基于PMC的连杆零件数控机床自动夹具设计与实现

为减小多次定位装夹引起的定位误差对零件加工精度影响,通过对连杆零件加工工艺分析,提出以零件不需加工的设计基准面为定位基准,以数控机床自身气源为动力、PMC为控制装置的工序集中式自动夹具设计理念。经设计夹具结构、气动系统和控制系统等,完成了基于PMC的连杆零件数控机床自动夹具制作。该夹具结构简单、定位准确、夹紧可靠、稳定性好。实验证明:利用该夹具加工连杆零件,连杆零件加工表面相互位置精度得到了一定程度的提高。     

基于铰杆-杠杆串联增力机构的双向浮动夹紧气动夹具

设计了一种基于铰杆-杠杆串联增力机构的双向浮动夹紧气动夹具,分析了其工作原理和性能特点,给出了夹紧力的计算公式.该夹具结构简单紧凑,且以洁净的压缩空气为工作介质,绿色化特征突出.同时由于采用二级增力机构,解决了一般气压传动夹具因压力较低而导致夹紧力不足的缺点.     

基于工序集中要求的轮辋车铣复合夹具设计

提出基于车铣复合工序集中的数控加工工艺方案,设计出一种车铣复合夹具装置。以二维平面装夹方式,分析轮辋工件的可装入性和取出性,确定轮辋工件的夹紧点位置。基于平面机构运动学的原理,分析车铣复合夹具中其中一个卡爪夹紧的运动轨迹,进而设计一种能够减少气缸工作行程的快速夹紧机构,该夹具装置夹紧方便可靠。     

变速箱拨叉轴圆弧槽铣夹具的设计及制造

根据变速箱拨叉轴上圆弧槽相对位置准确、系列拨叉轴可以在一套夹具上装夹、多个零件同时加工的要求,设计了一种分体式气动铣床夹具。该夹具采用定位块限位拨叉轴端面、燕尾面支承拨叉轴外圆的定位方式,对工件外圆多点气动夹紧;通过两级增力机构,增大夹紧力;柔性传动力矩,消除了交变铣削力作用产生的振动。依据计算的切削力选择了气缸规格。最终实现了工件在夹具中成组布置,提高了生产效率,保证了加工质量。     

FMS的夹具系统

文章简要介绍国内外柔性制造系统(FMS)所采用的夹具系统,其中包括通用夹具、专用夹具、成组夹具及组合夹具,并指出组合夹具为工业化国家目前FMS普遍采用的夹具系统;同时文章着重介绍了柔性数控改夹紧装置,对其结构、工作原理及特点作了较为详尽的描述.该装置由于可以节省价值较为昂贵的交换工作台和具有较大的柔性而成为FMS及自动化车间的工件夹持系统.组合夹具和柔性数控改夹紧装置将是FMS夹具系统的发展方向.     

精密阀芯径向孔钻床夹具设计

针对某精密阀芯外圆表面径向孔尺寸和位置精度高、加工质量不稳定的情况,设计一种采用V形槽反装定位、偏心轮装置快速夹紧的专用钻床夹具。详细分析了径向孔加工钻床夹具的定位和夹紧方案,计算出定位元件关键尺寸,阐述夹紧装置的原理和工作过程。经夹具精度分析与验算,发现所设计的夹具完全能满足精密阀芯径向钻孔的高精度要求。该夹具操作简便、适应性强、工件加工质量稳定,为机械行业销轴类零件高精度径向孔钻床夹具的设计提供了参考。     

气动夹紧装置

文章介绍一种新开发的气动夹紧装置。该装置适用于对尺寸相差较大的工件进行夹紧,并且夹紧力可根据工件做相应的调整,较之以前的夹紧装置适用范围大,且安全可靠。图2幅。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.